volves total accountability for the use of the veterinarian-recommended extra-label product) can access the database or be referred to a professional pharmacologist to obtain information on the use, dose, and suggested withdrawal interval for an extra-label product. A distinction is made between a withdrawal interval and a withdrawal time. Only FDA can establish a withdrawal time, as the term is used in its legal application. FARAD establishes a conservative withdrawal interval or withdrawal time period, to provide a large margin of safety in eliminating residues from treated animals. In addition, FARAD makes no claims as to the efficacy of the intended treatment and responds only to inquiries from licensed veterinarians with suggestions for withdrawal intervals and periods. The use, dose, and withdrawal specifications listed in FARAD are obtained from several sources, including international compendiums of the same or similar products and formulations that are already approved abroad, and from published literature citations and data extrapolations based on referenceable data that can be used for the specific applications (Craigmill, A. 1998. FARAD, personal communication).
It would be desirable to improve the process of reviewing and approving animal drugs at CVM to enhance the availability of safe and efficacious drugs for use in food animals and companion animals under CVM-established conditions of use. Drug manufacturers and FDA should set boundaries for safe and effective use of drugs in animals as they do in humans. Approvals are needed for the dosage ranges (rather than for specific dosages) found to be minimally effective and maximally nontoxic, and withdrawal times for maximum dosages should be established. Local evaluations and decisions by veterinarians with appropriate training in drug prescription are needed to optimize effectiveness and ensure the safety of animals and consumers. However, if the issue of animal drug availability is not addressed aggressively, the legal extra-label drug use actually could be a deterrent to the animal drug industry in its attempts to discover and develop new pharmaceutical products.
Given current drug efficacy requirements, relatively few food-animal species and a small number of diseases or production improvement uses are seen by the animal health industry to warrant the risk and capital investment now required for successful drug development. If those drugs or other new drugs are to be made available to a broad range of species, efficacy requirements must be interpreted to maximize rather than limit the potential of a drug for approval.
Clinical trials need not be the sole or predominant measure of a product’s effectiveness. The realities of livestock production and drug use are that, in the case of food animals raised in flocks or herds, any drug product will be tested quickly in the marketplace, and those found uneconomical or ineffective will be eliminated. To remedy many of these problems and facilitate the approval of